Steyer said he is also "doubling" his push for President Donald Trump's impeachment, which he has already backed with a $20 million national advertising campaign. That campaign, called "Need to Impeach," has helped Steyer build a massive email list.

He announced the moves Monday at a news conference in Washington that was heavily attended by political reporters anticipating a possible 2018 run for the Senate or governor in California or evenBong a presidential bid in 2020.